To calculate the <span>surface area of a composite figure you must apply the formulas for calculate the area of each figure that is part of the composite figure and then, you must sum all the areas calculated.
For example, is the composite figure is form by a triangle and rectangle, the surface area of the composite figure will be:
SA= Area of the triangle+ Area of the rectangle= (bh/2)+bh</span>
First separate the composite into component figures. Then find the surface area of each figure. A two-dimensional net can be used to find the surface area. Add the surface areas of the components. Then, subtract or exclude the areas of the figures that are shared.